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Power Fc Problem - Starting Rpm..

Lunatic Dancer
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Lunatic Dancer Collaborator

Lunatic Dancer

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Posted

When the car is cold, ie. overnight - starting in morning...

the rpm shoots to around 2000rpm...

which is quite normal...

my problem is it does this EVERYTIME i start the engine...

whether its coldstart in morning, after a hot run or after driving normally...

idleing fine...shut off....start and shoots to 2000rpm as if its cold start..

holds for a while etc...

its getting annoying, i've tried adjusting the water temp correction but didn't

seem to help, unless i'm doing it wrong..

stock ecu was fine...

any ideas? or better yet happened to someone and fixed it?

cheers,

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Lunatic Dancer Collaborator

Lunatic Dancer

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Busky - my idles at 900.....do you mean A/C? they are at 1050 but I've already removed all the gear...

Paul - Nah brand new unit...not sure if I can name names...so..just before the dyno after I put it in

I asked the tuner about the idle procedure (10min etc etc) and he said it wasnt needed.....though

it did idle for bout 5+ mins while he was checking the settings...inj etc...

maybe I should write down all the settings (fark :angry: ) and then initialize and do the idle procedure?

and then input it all back in? :wub:

paulr33 Grand Master

paulr33

Posted
Posted

5 minutes is not long enough. it cleary states in the manual (albeit in japanese) that it takes 30 minutes. i short cut my procedure and let it idle for about 8 minutes and the result was it would crank, start and stall. doing the procedure properly gave it a proper idle.

if it was me, i would write down the IGN map, INJ map, AIRFLOW meter table, WATER temp table and any other settings, is it a mild to stockish GTST or turbo/injector change?

then do the idle procedure, and drive it around for a day or so. make sure you are happy with the idle etc (and the problem is gone) then put the numbers back in

Lunatic Dancer Collaborator

Lunatic Dancer

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ok i've done all the init thing....and the idle learn...

problem is it is still doing it... =\

so i'm thinking it must be the settings...

can anyone tell me what the water temp correction exactly does? as its got two

figures that you can change for each...

also how do I work out the injector size etc....I know the stock / new X 100 thing but

where do i find out the ms for them? they're nismo 740cc...

another thing, with the air flow voltages......should all of them be the same?

as in vg30 with another vg30...or does it have to be set for the specific vehicle?

paulr33 Grand Master

paulr33

Posted
Posted

water temp correction, is as the name implies, correction based on water temp. as the engine heats up, so does the water temp, as it warms up it can aim for its optimal correction of 1.0 for fuel and ignition timing. when its colder it needs to be a bit more rich and a bit less ign timing and this increase on a scale down to -30deg water temp. so as the engine warms itself up, the timing and fuel alter accordingly to reach the ideal temp of around 80deg.

you shouldnt have to adjust water temp correction, out of the box should be ok for most applications. you need to make sure youve dialed in the injector settings correctly. do you get any smoke on idle out the zorst?

for the z32 you simply select VG30 on the menu, and it should idle and run ok but it does need to be dyno tuned to work and be safe (ie: put the numbers back in).

how long does it stay at 2000rpm for if you cold start it in the morning?

does it eventually drop to normal sooner or later, like if you left it idle for 20 minutes, would it drop to normal idle eventually? or only if you go a tap revs a few times.

next time it does it, try turning on demister, wait a few seconds then turn it off. also when its high, do monitor 8 CHANNEL monitor everything except BOOST and SPEED and paste up what is displayed

also check SENSOR / SW CHECK for anything that is coming on and off like in a pattern and also post up which ones are ON (black dot) and the voltages for the other sensors

Cubes Grand Master

Cubes

Posted
Posted

I think its more of a mechanical problem.

Whats the little cold start air control valve called.. IAC or something..

Maybe the temp sensing bit is buggered or oversensitive.

Maybe you are experiencing the start of a vacuum leak, when it all warms up things expand and the high idle fades to normal?

I can't see the powerfc in its self raising rpm to 2000rpm when cold as it doesn't have the capability to do so 'only' when cold.

Running rich or lean won't raise rpm to 2000rpm, HOWEVER something mechanical can.

Lunatic Dancer Collaborator

Lunatic Dancer

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thanks Paul...I was thinking that...so the numbers are for the fuel cells I take it.

Basically at cold start it will hold 2000rpm for up to 20-30 secs...then drop slowly to 900....quite a while..

After everything is warmed up and I shut the car and restart it will jump to 2000rpm and hold for probably

15secs and drop to 900rpm quicker than cold start...

I will try out the thermister thing tomorrow.....and also the figures and sensors...

Cubes - I too was thinking it would be something mechanical but i've double checked all vacumm stuff etc.

Also before injector / afm / pfc , I never had this problem with the stock ecu...

Lunatic Dancer Collaborator

Lunatic Dancer

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Paul - your question on the sensors got me thinking. Right now under functions the 02 feedback is currently

set to off. After Initializing I turned it off before starting the car first time, should it have been on?

I now realise that most tuners turn it off during the tune and back on afterwards, but since my case this

did not happen I thought it was the right setting to keep....

Now does this setting have anything to do with it or am I running around in circles..?

Cubes Grand Master

Cubes

Posted
Posted
2000rpm for up to 20-30 secs...then drop slowly to 900
jump to 2000rpm and hold for probably

15secs and drop to 900rpm

Definitely look at the mechanical side of things as the fueling will not raise rpm and do what you are stating.

1. IAC (Cold start idle control valve, this allows air in to the plenum as to raise idle when the motor is cold, as the motor warms it slowly closes)

2. Coolant temp sender. (Take note of how it reacts on a cold and warm start, obviously the warm start voltage will be very similiar as to when it was running)

3. While your there ensure idle rpm is set correctly. Disconnect the idle control solanoid plug and ensure idle rpm is a bee's dick under the a/c off value contained within the pfc. It shouldn't flick over this value. Tripple check all vacuum hoses, not just at the motor but carbon cannistor also.

4. The inj. correction should be set as followed...

old injector size / new injector size * 100.

So SR20? 444 cc / 740cc * 100 = 60%.

The inj. correction does work extremely well, I found mine to run fairly rich once up on boost but off boost area's were pretty spot on.

The o2 sensor was easily able to rim fuel quickly. So turn on closed loop feedback.

Leave all water temp correction alone. If its warm starting and cold starting fine (as in it starts) then leave the starting injector time alone also.

I have found pushing in more starting injector ms will flare rpm up on starting but its not like you state; its similiar to one reving the car quickly with idle settling on what it would depending on the conditions (cold or warm)

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